Told that this might violate postal regulations, his spokeswoman, Barbara Morgan, said, “I think that if it’s not all the way in, it’s OK.’’ Postal regulations state that only stamped US mail delivered by letter carriers can be left in boxes.

There’s no reference to how far nonstamped mail can permissibly penetrate.

But Morgan said she’d try to find out.

“While Anthony was careful to leave the fliers mostly outside the boxes, he will cooperate fully in any investigation of ‘mailboxgate,’ ’’ she said.

Weiner also appeared at a “family day” celebration on the Upper West Side — without his family.

Asked why wife Huma Abedin and baby son Jordan were AWOL, he sniped at a reporter, “Are you married? Do you have friends? Why aren’t they with you?’’

Asked if his wife will be campaigning with him at future events, he said, “You can expect that.’’

And will she join him at fund-raising events? “You have to wait and find out,’’ he said. “Are you at the edge of your seat?’’